CAYSTON has low systemic exposure

SPUTUM CONCENTRATIONS

  • Mean sputum concentrations of aztreonam 10 minutes after dose administration in patients receiving CAYSTON (75 mg) 3 times a day for 28 days are shown below*:
Day 0
984 mcg/g
Day 14
793 mcg/g
Day 28
715 mcg/g

* There was considerable variability observed between patients.

PLASMA CONCENTRATIONS

  • Mean peak plasma concentrations were reached 1 hour post dose in patients receiving CAYSTON (75 mg) 3 times a day. Values shown below:
Day 0
0.55 mcg/mL
Day 14
0.67 mcg/mL
Day 28
0.65 mcg/mL

† There was considerable variability observed between patients.

  • In contrast, serum concentration following a one-time, 30-min IV administration of aztreonam for injection (500 mg) was approximately 54 mcg/mL.
  • There was no systemic accumulation of CAYSTON.

ABSORPTION

  • Evaluation of plasma and urine aztreonam concentrations in patients following administration of CAYSTON indicated low systemic absorption of aztreonam.
  • About 10% of the total CAYSTON dose was excreted in the urine as unchanged drug, as compared to 60%-65% following IV administration of aztreonam for injection.